NetworkServerAbstract: add constructor taking NetworkMessageEventListenerManager...

NetworkServerAbstract: add constructor taking NetworkMessageEventListenerManager, {set,get}Title(), missing javadocs, simplify logging

Modify constructors so there is one that will take an external
NetworkEventListenerManager rather than only creating one internally.
Make less specific argument list versions call their more specific
alternative.

Introduce {set,get}Title(). This supports clients that, after login, need to include
the userID in outgoing NetworkMessage, MessagePresence, and other data.

Simplify logging using a local project-standardised logp().